Worm Wheel Resin Molding for Uniform Tooth Accuracy
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Solution Overview
Problem
The existing method for manufacturing worm wheels results in inconsistent cooling and filling of molten resin, leading to shape accuracy issues and potential damage due to cold slugs, which can cause abnormal noise and vibration at the meshing portion between the wheel and worm teeth.
Innovation Solution
A method involving an annular or arc-shaped injection gate positioned to face the inner circumferential surface of a tubular eave portion on the inner wheel element, ensuring uniform resin distribution and avoiding cold slug formation by using a hot runner with an open gate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If molten resin is fed from the injection gate into the cavity, then the outer wheel element is formed by injection molding, but the molten resin flows unevenly causing shape accuracy deterioration and cold slug formation
Solution Approach 1:
The patent applies preliminary action by designing the injection gate to face the inner circumferential surface of the eave portion before injection molding begins. This positioning ensures that molten resin flows uniformly into the cavity from the start, preventing cold slug formation and ensuring consistent shape accuracy of the wheel teeth without requiring post-processing corrections
Solution Approach 2:
The patent applies local quality by positioning the injection gate at a specific location (facing the inner circumferential surface of the eave portion) rather than using a generic gate position. This localized positioning optimizes the flow distribution of molten resin specifically for this mold cavity geometry, ensuring uniform filling and eliminating cold slugs in critical areas
2Manufacturing precision
If the injection gate is positioned to face the inner circumferential surface of the eave portion, then uniform resin distribution is achieved, but the gate design becomes more specific and complex
Solution Approach 1:
The patent applies universality by designing the injection gate to serve multiple functions simultaneously: it provides resin injection, ensures uniform flow distribution, prevents cold slug formation, and positions itself optimally relative to the eave portion structure. This multi-functional design achieves uniform resin distribution without requiring additional separate components or complex positioning mechanisms
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures consistent shape accuracy and durability of the wheel teeth by preventing cold slug formation and ensuring uniform resin cooling, reducing the likelihood of noise and vibration during operation.
Implementation Method 1
feeding the molten synthetic resin from an annular or arc-shaped injection gate toward a pocket portion
Implementation Method 2
using a hot runner with an open gate
Implementation Method 3
ensuring uniform resin cooling
Data Source
AI summary
A method for manufacturing a worm wheel including an inner wheel element including a side plate portion and a tubular eave portion, and an outer wheel element including a wheel tooth portion on an outer circumferential surface thereof, and coupled and fixed to the inner wheel element in a manner of covering a radially outer portion of the side plate portion and the eave portion, the method includes: molding the outer wheel element by disposing a mold around a radially outer portion of the inner wheel element, and feeding the molten synthetic resin from an annular or arc-shaped injection gate toward a pocket portion that is continuous over an entire circumference of a cavity present between an inner surface of the mold and a surface of the inner wheel element and that is present on a radially inner side of the eave portion.